1. Field of the Invention
The present invention relates to a position information processing system for a mobile such as a motor vehicle.
2. Description of the Related Art
There have been provided position information processing systems each of which is used for showing the current position of a vehicle and/or the distance between the current position of the vehicle and the destination which are set to be displayed. Such a system is called a "Navigation System".
One of such systems is shown in FIG. 1. In this system, display device or atlas gauge AG and a specific atlas MP, which is commercially available, are used. The atlas gauge AG includes a substantially U-shaped frame 1 and a transparent rectangular thin plate 2 which is held at its three sides by the three sides of the atlas gauge AG. A plurality of equi-spaced indicators are provided in each of a lateral side 1a and a longitudinal side 1b. On the plate 2, there are printed a plurality of lateral lines and a plurality of longitudinal lines both of which constitute a lattice configuration as a whole. The lateral lines BL and longitudinal lines BL are opposed to corresponding indicators 3H in the lateral side 1a and corresponding indicators 3V in the longitudinal side 1b of the frame 1, respectively. When the system is in use, as shown in FIG. 2, the atlas MP is set under the plate 2, through which a map on a specific or selected page can be seen. The provision of the plate 2 on the page of the atlas MP should be established in such a manner that a terminal point MPO is set to be in alignment with a corner 1c.
Thus, in this system, a specific point on the page can be represented as the combination of a lateral length and a longitudinal length both of which are measured from the corner 1c of the frame 1 and can be shown by lighting the corresponding indicators 3H and 3y. In actuality, on the basis of the previously known latitude and longitude of the criteria point PO of the specific page and a reduced scale rate of the map on the page, lateral and longitudinal distances of the point Px on the map relative to the criteria point PO brings latitude and longitude of the point Px. This leads that subject to the agreement of the criteria point of the map PO and criteria point 1c of the atlas gauge 1, the current position can be presented by lighting one of laterally arranged indicators 3H and one of longitudinally arranged indicators 3V based on latitude and longitude of the current position. The current position can be obtained by receiving electromagnetic waves from one or more satellites of GPS (Global Positioning System). For example, when a desired position is represented by the combination of one of the lateral indicators 3H which is lit in turn and one of the longitudinal indicators 3V which is lit in turn, the input of the represented position into the device can be understood for the device as latitude and longitude of the desired position.
However, in this system, latitude and longitude of the criteria point of each page, lateral length and longitudinal length of each page, the offset of the criteria point from the criteria point 1c of the atlas gauge 1 in each page, the scale reduction rate of the map on each page, and related information should be memorized. In order to indicate the current position, the page number of the atlas to which the current position belongs should be known. If it is desired that this system can be available through a specific nation such as Japan, a large amount of pages of one or more atlases should be searched, which takes a long time. Therefore, it is desirable to have a prompt or quick search of a specific page of the map in which the current position is to be included.